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...8 COMMUNICATION
...8.4 Communication Examples
e) Command –
STX
STX
W
11
LA 70 ETX
Alarm A trip point
Controller number eleven
'Write' command
Start of text
Reply – 11LA70
11
A1 70
ACK
Command understood
Alarm A setting is 70
Controller number eleven
Security level 1 access
(0 = no access, 1 = access)
Security level 2 access
(0 = no access, 1 = access)
Power failure status
(0 = no power failure, 1 = power failure)
Self-tune state
(0 = off, 1 = on)
Auto/Manual state
(0 = auto, 1 = manual)
Set Point type
(0 = local, 1 = second)
10
W11A170
E E TX
End of text
Write to 70
ACK
MSB
11 10
9
8
Fig. 8.7 Instrument Status
f) Command –
STX
W
'Write' command
Start of text
Reply – 0503
05
03
NAK
Error code 3
Controller number five
i.e. 'L2' in the original command is not
a recognised 'Write' parameter. The
'L2' mnemonic can only be used with
the 'Read' command.
7
6
5
4
3
2 1
STX
W05L21
E E TX
05
L2
1 ETX
End of text
Relay 2
energised
Relay 2 state
Controller number five
N N AK
Command not understood
Unacknowledged alarm
(0 = no alarms unacknowledged,
1 = alarms unacknowledged)
Alarm 2 relay state
(0 = relay off, 1 = relay on)
Alarm 1 relay state
(0 = relay off, 1 = relay on)
0
LSB
Process variable failure
(0 = no failure, 1 = failure)
Remote set point failure
(0 = no failure, 1 = failure)
Position feedback failure
(0 = no failure, 1 = failure)
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